Electronic antenna scanning switch



May 24, 1960 A. E. RATKEVICH ELECTRONIC ANTENNA SCANNING SWITCH I 2 Sheets-Sheet 1 Filed March 31, 1958 TO RECEIVER ADAM E. RATKEVICH BY m & jaw-x.

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May 24, 1960 A. E. RATKEVICH ELECTRONIC ANTENNA SCANNING swn'cu 2 Sheets-Sheet 2 Filed March 31, 1958 E i 1 5.. w

RECEIVE SQUARE WAVE TRANSMITTER PULSE GENERATOR RECEIVER Fig. 5

INVENTOR. ADAM E. RATKEVICH ELECTRONIC ANTENNA SCANNING SWITCH Adam E. Ratkevich, San Diego, Calif., assignor to Ryan Aeronautical Co., San Diego, Calif.

Filed Mar. 31, 1958, Ser. No. 725,437

6 Claims. (Cl. 333-7) The present invention relates generally to microwave antenna systems, and more particularly to an electronic scanning switch for antenna lobing.

The primary object of this invention is to provide an antenna scanning switch which is entirely electronic in nature and has no moving parts, so eliminating microphonics due to vibration and permitting a very high rate of scan since the speed isnot limited by mechanically moving parts.

:Another object of this invention is to provide an antenna scanning switch utilizing intercoupled ferrite core turnstile switches controlled by square wave pulse energy to scan a plurality of directional lobes in a high speed sequence.

Still another object of this invention is to provide an antenna scanning switch which introduces no noise modulation on the incoming signal and is thus ideally suited for use with continuous wave radar equipment.

Another object of this invention is to provide an antenna scanning switch in which each lobe is scanned sequentially, the discarded lobe signals being effectively absorbed to prevent interference with the scanned lobe signal.

Finally, it is an object to provide an antenna scanning switch of the aforementioned character which is simple and convenient to make and use and which will give generally eflicient and durable service.

With these and other objects definitely in view, this invention consists in the novel construction, combination and arrangement of elements and portions, as will be hereinafter fully. described in the specification, particu:.

larly pointed out in the claims, and illustrated in the drawings which form a material part of this disclosure and in which:

Figure 1 is a front elevational view of the scanning switch, the feed coupling and portions of the waveguides being omitted;

. Figure 2 is a sectional view taken on the line 2-2 of Figure 1;

Figure 3 is a sectional view taken on the line 3--3 of Figure 2;

Figure 4 is a sectional view taken on the line 44 of Figure 2; and

Figure 5 is a diagrammatic showing of the scanning switch incorporated in a radar system.

Similar characters of reference indicate similar or identical elements and portions throughoutthe specification and throughout the views of the drawings.

- Referring now to the drawings in detail, the scanning switch comprises three turnstile junction switches 10, 12 and 14 connected in a series-parallel arrangement. The turnstile switch is mounted at the center of a waveguide T 16 from the ends of which are extended two parallel waveguide arms 18 and 20, the turnstile switch 12 being mounted adjacentthe end of the arm 18 and the turnstile switch 14 being mounted adjacent the'end of the arm 20. Extending from the waveguide 'l'. 16,- on .the opposite side from the central arm 22 of- 2,938,176 Patented May 24, 1960 1 the T, is a load assembly 24, while coextensive with the ends of the Waveguide arms 18 and 20 are two further load assemblies 26 and 28, respectively. At the turnstile switch 12, a pair of opposed feed waveguides 30 and 32 are connected to the waveguide arm 18 normal to that arm, while at the turnstile switch 14 a pair of opposed feed waveguides 34 and 36 are connected to the waveguide arm 20 and disposed normal thereto. All of the feed waveguides 30 to 36 are coupled to a feed adaptor plate 38 which is shaped to fit together with a four lobe antenna feed, such as that described in my copending application Serial No. 725,433, filed March 31, 1958, for a receiving antenna feed. The feed waveguides 30 to 36 are formed so that their ends are arranged at the adaptor plate 38 substantially in a diamond pattern, as indicated in Figure 1 in which the feed waveguides 30 and 34 are shown in dash line, this arrangement corresponding to the structure of the above mentioned antenna feed. The actual arrangement of the feed waveguides may be varied, however, to suit a specific feed element.

The turnstile switch 10 comprises an electromagnetic coil 40 which is wound on a cylindrical coil former 42 having a flange 44 at one end and a flange plate 46 at the other end. Within the coil former 42 is a ferrite rod or core 48 which is supported and enclosed in a pair of core holders 50 of plastic material or the like, said core holders having sockets 52 to receive the core and being shaped to fit closely inside said coil former. The outer end of the coil former 42 is closed by a cover plate 54 suitably secured to the flange 44 by screw or the like, and the coil assembly is secured by means of the flange plate 46 to a mounting plate 56 fixed to the waveguide T 16 centrally over the junction of the T bar and its central arm 22. The turnstile junction is balanced, as hereinafter described, by a balancing pin 58 which is fixed to the waveguide T 16 in axial opposition to the ferrite core 48, said pinhaving a hub portion 60 with a opening 66 in the waveguide wall and serves to retain.

the holders and core in place, as in Figure 2. The turnstile switches 12 and 14 are identical to the turnstile switch 10, the switch 12 being positioned cen-L- trally at the junction of waveguide arm 18 with the feed waveguides 30 and 32, and the switch 14 being centrally located at the junction of waveguide arm 20 with the feed Waveguides 34 and 36.

The load assembly 24 comprises a waveguide stub 68 extending from the T 16 opposed to the central arm 22, said stub having an end flange 70 to which is secured a cap plate 72. Within the waveguide stub 68 is a closely fitting holder block 74 of plastic or the like, having a central longitudinal socket 76 in which is held a polyiron rod or load 78, said holder block having a reduced diameter aperture 80 at one end of the socket, opening into the waveguide T 16 such that said aperture and said polyiron load are aligned radially'of the pin 58. The holder block 74 is retained in place by a lock pin 82 fixed transversely across the waveguide stub 68 against the end of said block.

The load assemblies 26 and 28 are identical in construction to the load assembly 24 and are housed inwaveguide stubs 84 and 86, which are integral and coextensive with the ends of waveguide arms 18 and 20, respectively.

The scanning switch is used in an antenna system such as that shown in Figure 5, the system including a 3 my copending application for a coaxial antenna, Serial No. 725,434, filed March 31, 1958, but the scanning switchis also applicable to other types of antennas. The scanning switch is connected to the receiver feed 96 and an output waveguide 98 extends from the central arm 22 to a receiver crystal 100, which in turn is connected to a receiver 102. The scanning switch is operated by a suitable square wave pulse generator 104- connected to the coils 46 of the turnstile switches 10,-12 and 14, the circuitry being such that the coils 40 may be energized in a predetermined sequence with any desired polarity.

In operation, the receiver feed 96 provides signals from four lobes of the antenna 94 to the feed waveguides 30 to 36. For convenience of description the feed waveguides 3t), 32, 34 and 36 have been marked right, down, left and up, respectively, to denote the particular antenna lobe from which each signal is received. Each of the turnstile switches 10, 12 and '14 may be energized to deflect the signal energy from either of "its associated waveguides in either of two directions. The balancing pins 58 prevent microwave energy from passing directly across the turnstile switches and the polarity of each ferrite core 48 determines the direction of defiection of the energy. Thus by energizing the coils 40 in a simple sequence and reversing their polarity, also in sequence, the signal from each 'feed waveguide may, in turn, be directed to the output waveguide 98 for study by the receiver 102. A typical energy pattern is illustrated by the full line directional arrows in Figure 4, in which the signal from the right feed waveguide 39 is deflected into the load 26, while the signal from the down feed waveguide 32 is channeled along the arm 18. The polyiron loads 78 have the characteristic of being able to absorb microwave energy, the principle being well known in the art. Thus the unwanted signals are absorbed and do not cause interference with the signal selected for study, since the loads are situated well out of the field of the turnstile switches. At the turnstile switch 14, the signal from the left feed waveguide 34 is deflected along the arm 20, while the signal from the up feed waveguide 36 is absorbed by the load 28. At the turnstile switch 10, the signal from the arm 18 is deflected into the central arm 22, while the signal from arm 20 is absorbed by the load 24. In this manner, the signal from the down feed waveguide 32 is selected for study and is conducted to the receiver. By reversing the polarity of all coils 40, the energy pattern shown in broken line directional arrows is obtained, the signal from the up feed waveguide 36 being selected for study in this instance. It will be evident that by energizing the coils 40 and controlling their polarity in a particular sequence, the four antenna lobes may be scanned in order. Since the switching is electronic rather than mechanical, the scanning may be accomplished at very high speed and the four lobe signals compared at the receiver 102 to determine the location and direction of motion of a target detected by the equipment. The lack of'moving parts reduces microphonics and other noise modulation to a minimum and eliminates interference with the incoming signal, so that the device is suitable for use with sensitive and precise equipment such as continuous wave Doppler radar.

The operation of this invention will be clearly comprehended from a consideration of the foregoing description of the mechanical details thereof, taken in connection with the drawings and the above recited objects. It will be obvious that all said objects are amply achieved by this invention. 7

It is understood that minor variation from theform of the invention disclosed herein may be made without departure from the spirit and scope of the invention, and that the specification. and'draw-ings. are to be, considered. as. merely illustrative rather than limiting;

Lclaim:

V ;1. antenna. switch .fonconncction to a 7 plural lobed source of microwave signal energy, comprising: three turnstile junction switches each having a magnetizable core element; opposed Waveguide arm elements extending from one of said switches, the other switches being mounted adjacent the ends of said arm elements; an output waveguide communicating with the intersection of said arm elements at said one switch; means for directing microwave energy from at least one of the lobes to said arm elements at each of said other switches; load elements capable of absorbing microwave energy operatively mounted adjacent each of said switches; and means for energizing and changing the polarity of said core elements in sequence, whereby l signal energy from one of the lobes at a time may be directed to said out-putwaveguide while the energy from the remaining sources is directed into the load elements.

2. An antenna scanning switch for connection to a plural lobed source of microwave signal energy, comprising: three turnstile junction switches each having a magnetizable core element; opposed waveguide arm-elements extending from one of said switches, the other switches being mounted adjacent the ends of said arm elements; an output waveguide communicating with the intersection of said arm elements at said one switch;

opposed pairs of feed waveguides communicating with said arm elements at each of said other switches, said feed waveguidm being connected to the individualzs'i'gna'l source lobes; load elements capable of absorbing microl wave energy operatively mounted adjacent each of said switches; and means for energizing and changing the polarity of said core elements in sequence, whereby sig-' nal energy from one of the lobes at a time may be directed to said output waveguide while the energy from the remaining source is directed into the load elements.

3. An antenna scanning switch for connection to a plural lobed source of microwave signal energy, comprising: threeturnstile junction switches each having a magnetizable core element; opposed waveguide arm elements extending from one of said switches, the other switches being mounted adjacent the ends of said arm elements; an output waveguide communicating with theintersection of said arm elements at said one switch; opposed pairs of feed waveguides communicating with said arm elements at each of said other switches, said feed waveguides being connected to the individual signal source lobes; load elements capable of absorbing microwave energy operatively mounted adjacent each of said switches; the axes of said core elements being substantially normal to the intersecting axes of the respective waveguide elamcnts at each of said switches; and means for energizing and changing the polarity of said core elements in sequence, whereby signal energy from one of the lobes'a't a time may be directed to said output waveguide while I the energy from the remaining sources is directed into the load elements.

4. An antenna scanning switch for connection to a plural lobed source of microwave signal energy, comprising: three turnstile junction switches each having a magnetizable core element; opposed waveguide arm elements extending from one of said switches, the other switches being mounted adjacent the ends of said am elements; anoutput waveguide communicating with the intersection of said arm elements at said one switch;opposed pairs of feed waveguides communicating with. said arm elements at each of said other switches, said feed waveguides being connected to the individual signal source lobes; load elements capable of absorbing microwaveenergy operatively mounted adjacent each of said switches; the axes of said core elements being substantially normal to the intersecting axes of the respective waveguide elements at each of said switches; balancing pins mounted coaxlally with each of said core elements andextending axially across the waveguide elements at each switch;

. and means for energizing and changing the polarity of said core elements in sequence, whereby signal energy from-.onevof the: lobes: at atimc'may be'directcd maid output waveguide while the energy from the remaining sources is directed into the load elements.

5. An antenna scanning switch for connection to a plural lobed source of microwave signal energy, comprising: three tumstile junction switches each having a magnetizable core element; opposed waveguide arm elements extending from one of said switches, the other switches being mounted adjacent the ends of said arm elements; an output waveguide communicating with the intersection of said arm elements at said one switch; opposed pairs of feed waveguides communicating with said arm elements at each of said other switches, said feed waveguides being connected to the individual signal source lobes; polyiron load elements capable of absorbing microwave energy mounted at the ends of said arms and normal to the common axes of said opposed pairs of feed waveguides, and a further polyiron load mounted at said one switch in axial opposition to said output waveguide; the axes of said core elements being substantially normal to the intersecting axes of the respective waveguide elements at each of said switches; balancing pins mounted coaxially with each of said core elements and extending axially across the waveguide elements at each switch; and means for energizing and changing the polarity of said core elements in sequence, whereby signal energy from one of the lobes at a time may be directed to said output waveguide while the energy from the remaining sources is directed into the load elements.

6. An antenna scanning switch according to claim 1, and wherein the intersection of said arm elements and said output waveguide defines a T, said arms having 0&- sct portions substantially parallel and on opposite sides of said one switch, whereby a compact structure is achieved.

References Cited in the file of this patent UNITED STATES PATENTS Kline Sept. 12, 1950 Dicke Aug. 17, 1954 

